1. Field of the Invention
The present invention relates to a top entry top exit wiring duct or wireway for routing cables, wires or tubes to terminal devices.
2. Description of the Prior Art
Wiring ducts in the form of U-shaped channels are known for use in holding, supporting, retaining and distributing conductors in an orderly manner to terminal devices for components located on a common surface area. It is the generally accepted procedure and for the sake of neatness, convenience and safety and ease of repair, to place the conductors in one or more ducts which must be spaced from the terminal devices to allow room for preparing or dressing and attaching the conductors to the terminal devices. The U-shaped channels are generally made of a relatively flexible plastic material having good insulation quality. The U-shaped channels are attached to the panel frame by way of conventional fasteners passed through appropriate mounting holes disposed in the base of the channels, or they are held in position by means of clips or the like. The conductors required for a particular installation are routed to the terminal devices generally through slots in the sidewalls of the ducts. The side wall slots may be in the form of circular holes or elongated slits which are open to the edge of the channel side wall, preferably by way of a restricted passage. Covers are provided to enclose the top of the duct to retain the conductors in the duct. These covers are often difficult to assemble due to bulging of the side walls of the ducts. Patents representative of this type of duct include the following: U.S. Pat. Nos.: 1,639,310; 2,896,009; 3,321,571; 3,631,300; 3,763,401; 3,890,459; 3,906,146; 3,909,505; and 4,092,700.
One of the major problems associated with mounting components in this manner is that the terminals to which the electrical conductors are attached are close to the mounting surface, and the high side walls of the wiring duct restrict free access to the terminals, making the task of attaching the wires very difficult. This is due to the nature of the side exit type ducts which require a space between the duct and the particular terminal device in order to allow for side exit of the conductors regardless of the location of the terminal device or the elevation of the duct side walls. In order to alleviate this problem, the ducts are spaced from the terminal devices a distance sufficient to allow room for the technician to place his hand between the duct and the terminal device, thus increasing the overall size of the area required to support the conductor and the duct. These ducts are generally single channel type and additional ducts are required where separation of conductors is required.